Lateral hypothalamic serotonin inhibits nucleus accumbens dopamine: Implications for sexual satiety

Dopamine (DA) is released in several brain areas, including the nucleus acc umbens (NAcc), before and during copulation in male rats. DA agonists admin istered into this area facilitate, and DA antagonists inhibit, numerous mot ivated behaviors, including male sexual behavior. Serotonin (5-HT) is gener ally inhibitory to male sexual behavior. We reported previously that 5-HT i s released in the anterior lateral hypothalamic area (LHA(A)) and that a se lective serotonin reuptake inhibitor microinjected into that area delayed a nd slowed copulation. Our present results, using high temporal resolution m icrodialysis, (1) confirm previous electrochemical evidence that extracellu lar levels of DA increase in the NAcc during copulation and decrease during the postejaculatory interval (PEI) and (2) reveal that LHA(A) 5-HT can inh ibit both basal and female-elicited DA release in the NAcc. These findings suggest that the neural circuit promoting sexual quiescence during the PEI includes serotonergic input to the LHA(A), which in turn inhibits DA releas e in the NAcc. These findings may also provide insights concerning the inhi bitory control of other motivated behaviors activated by the NAcc and may h ave relevance for understanding the sexual side effects common to antidepre ssant medications.